Room 04 · Refinery
One of the hardest operations in the factory is merging.
The merge system is the deterministic authority that turns proposed branches into shared history — one writer per lane, one exact tested candidate, contracts that survive crashes.
Workers propose; the merge system decides
Many parallel workers produce candidate branches, but one repository must become one coherent history. The merge system is the only automated authority that can land work, and it earns that authority by being deterministic: one writer per lane, immutable attempts, and retries that create new fenced attempts rather than reopening old ones.
This station goes deep. Follow it in order:
- The merge controller — how a candidate is claimed, prepared, and advanced one proven step at a time.
- Verification gates — the testing system: one exact candidate SHA, one terminal verdict, green alone authorizes the push.
- Merge is not deploy — why “done” means source-complete, and how promotion is its own transaction.
- The reliability contracts — the invariants underneath it all: leases, fencing, terminals that never reopen.
When a merge genuinely conflicts, the factory does use AI — a bounded repair job proposes a resolution, but it has no merge authority and must re-enter as a fresh attempt that passes the complete gate.
The full station guide arrives with the new edition of the book.